The front lines in the Libyan civil war have largely stagnated since the popular uprising seeking to oust Gadhafi broke out in February. Rebels, backed by NATO’s air force bombings, control much of the country’s east and pockets in the west. But Gadhafi controls the rest from his stronghold in Tripoli, the capital.

Foreign ministers and other representatives of the so-called Contact Group on Libya said in a statement Friday that the “Gadhafi regime no longer has any legitimate authority in Libya.” They said the Libyan strongman and certain members of his family must go.

The group said it would deal with Libya’s main opposition group — the National Transitional Council, or NTC — as “the legitimate governing authority in Libya” until an interim authority is in place. In addition to the U.S., the 32-nation Contact Group on Libya includes members of NATO, the European Union and the Arab League.

Gadhafi, who has been in hiding, quickly rejected the decision and vowed never to surrender.

“I don’t care which countries recognize the rebels’ transitional council,” he said in an audio address broadcast to thousands of supporters in Zlitan, 90 miles (140 kilometers) southeast of Tripoli. “Tell NATO and other countries to pick up the white flag and ask our forgiveness.”

“You guys say that Gadhafi is over, then why are all these people demonstrating outside. The Libyan people will persevere. They will never give up,” he added, prompting supporters to fire guns in the air and set off fireworks.

The recognition of the Libyan opposition as the legitimate government gives foes of Gadhafi a major financial and credibility boost. Diplomatic recognition of the council means that the U.S. will be able to fund the opposition with some of the more than $30 billion in Gahdafi-regime assets that are frozen in American banks.

Contact Group representatives broke into spontaneous applause when U.S. Secretary of State Hillary Rodham Clinton announced U.S. recognition of the NTC, according to U.S. officials.

“The United States views the Gadhafi regime as no longer having any legitimate authority in Libya,” Clinton said. “And so I am announcing today that, until an interim authority is in place, the United States will recognize the NTC as the legitimate governing authority for Libya, and we will deal with it on that basis.”

Rebel spokesman Mahmoud Shammam welcomed the NTC’s recognition and called on other nations to deliver on a promise to release hundreds of millions of dollars in funds to the opposition. “Funds, funds, funds,” Shammam said, in order to stress the opposition’s demand.

He said the opposition hopes to hold elections within a year and resume oil exports very soon, saying the damage to oil facilities has been minimal and repaired. However, Shammam ruled out any new oil contracts until a new elected government is in place.

There had been concerns about whether the initial replacement government would represent the full spectrum of Libyan society. Human Right Watch urged the Contact Group on Libya to press the opposition to ensure that civilians are protected in areas where rebels have assumed control, citing abuses in four towns — Awaniya, Rayayinah, Zawiyat al-Bagul, and Qawalish — recently captured by rebels in the western mountains, including looting, arson and beatings of some civilians who remained when government forces withdrew.

In June, Human Rights Watch also criticized the rebel for arbitrarily detaining dozens of men suspected of supporting Gadhafi. This week, it criticized rebels in Libya’s western mountains for looting shops, homes and medical facilities in villages they’ve conquered.

Early on, some in the West feared the rebels contained radical Islamist elements. While a number of individual fighters have been found to have old connections to radical groups, none have risen in the rebel leadership, which insists it seeks to establish a democratic government based on a secular constitution.

A senior U.S. official said however, that the National Transitional Council won international recognition after gave assurances it would abide by its commitments and find a way forward for a truly democratic Libyan government.

The official, speaking on condition of anonymity to discuss private diplomatic conversations with the NTC and the other Contact Group members, said the assurances included upholding the group’s international obligations, pursuing a democratic reform process that is both geographically and politically inclusive, and dispersing funds for the benefit of the Libyan people.

“We believe them, we think that’s what they intend to do,” Clinton said of the opposition’s assurances.

The U.S. is impressed by the progress the NTC has made in laying the groundwork for a successful transition to a unified, democratic Libya which protects the rights of all of its citizens, including women and minority groups, she said.

“We think they have made great strides and are on the right path,” Clinton said. “The assurances that the NTC offered today reinforced our confidence.”

Asked why it took so long to recognize the NTC, Clinton said the U.S. administration analyzed the situation and wanted to make sure that the NTC’s actions accord with its statements, aspirations as well as its values.

“We really have acted in warp time in diplomatic terms, but we took our time to make sure that we were doing so based on our best possible assessments,” Clinton said.

Ahead of the meeting in Istanbul, a spokesman for the Libyan government said its members were ready to die in defense of the country’s oil against attacks by the rebels and NATO forces. “We will kill, we will die for oil,” Moussa Ibrahim said. “Rebels, NATO, we don’t care. We will defend our oil to the last drop of blood and we are going to use everything.”

The Contact Group statement called for the establishment of a cease-fire and the provision of humanitarian assistance to “normalize life.” It also urged a smooth transition to democracy, ruled out participation of “perpetrators of atrocities against civilians” in a future political settlement, and called on members to provide financial aid to the opposition, including the unfreezing of Libyan assets and helping the opposition to resume the production and export of oil.

The U.S. official said the recognition of NTC as the government of Libya would allow countries to help the opposition access additional funds. However, he stressed that more legal work needs to be done by some countries, including the U.S. and at the United Nations, to fully legalize that step.

The recognition does not mean that the U.S. diplomatic mission in the rebel-held city of Benghazi, Libya, is now an embassy. Titles of staff and names of offices will be decided in the coming days, the official said.